Eating More Fish Linked to Lower Risk of Depression

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People who eat a lot of fish may have a slightly lower risk of
depression, according to a new analysis of previous studies.

In their analysis, researchers looked at 26 studies that involved
a total of 150,278 people and examined the relationship between
depression and the
consumption of fish. Ten of the studies were conducted in
Europe and seven were done in North America, with the remaining
ones conducted in Asia, Oceania and South America.

When the researchers analyzed the studies conducted in Europe,
they found that the people who consumed the most fish had a 17
percent lower
risk of depression than those who ate the least amount of
fish.

When the researchers analyzed all the data by gender, they found
that the men who ate the most fish had a 20 percent lower risk of
depression than those who ate the least amount of fish. In women
who ate the most fish, their risk of depression was reduced by 16
percent, compared to the women who ate the least fish.

Although the associations between high fish consumption and lower
depression risk were found for the studies conducted in Europe,
they were not found for the studies conducted in the other
continents, the researchers noted. "This might [be] because a
smaller number of participants cannot reach statistical
significance easily," said study author Fang Li of Qingdao
University in Shandong, China.

Because the studies included in the analysis were observational
(the researchers did not, for example, ask people to start eating
more fish and measure the effects), a cause-and-effect
relationship between fish consumption and the risk of depression
could not be established, the researchers said.

Moreover, the researchers did not have information about the
types of fish the people in the studies ate, Li said. More
research is needed to see if the association between depression
risk and fish consumption varies according to the
type of fish consumed, the researchers said.

It is not clear why eating more fish may lower the risk of
depression, but there are several mechanisms that could be at
work in the link, the researchers said. For instance, previous
research has suggested that
omega-3 fatty acids in fish could alter the structure of
brain cell membranes. It could also be that other fatty acids in
fish modify the activity of the neurotransmitters dopamine and
serotonin, which are thought to be involved in depression, the
researchers said.

But it could also be that people who eat more fish are generally
healthier. "High fish consumption may also be related to a
healthier diet and better nutritional status, which could
contribute to the lower risk of depression," Li told Live
Science.

The new study was published today (Sep. 10) in the Journal of
Epidemiology & Community Health.